System and methods for leadless pacing using negative pressure

ABSTRACT

Disclosed herein is a system for delivering a leadless pacemaker having a housing with a proximal end. The system includes a guide catheter. The guide catheter includes a catheter shaft and a negative pressure attachment feature. The catheter shaft includes a distal end and a proximal end opposite the distal end. The negative pressure attachment feature is located at the distal end of the catheter shaft and configured to selectively negative pressure adhere with the housing of the leadless pacemaker.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/497,890, filed Apr. 26, 2017. The patent application identified aboveis incorporated here by reference in its entirety to provide continuityof disclosure.

INCORPORATION BY REFERENCE

All publications and patent applications mentioned in this specificationare herein incorporated by reference to the same extent as if eachindividual publication or patent application was specifically andindividually indicated to be incorporated by reference.

FIELD

The present disclosure relates to leadless cardiac pacemakers andrelated delivery systems and methods. More specifically, the presentdisclosure relates to catheter-based delivery systems and methods fordelivering leadless pacemakers.

BACKGROUND

Cardiac pacing by an artificial pacemaker provides an electricalstimulation of the heart when its own natural pacemaker and/orconduction system fails to provide synchronized atrial and ventricularcontractions at rates and intervals sufficient for a patient's health.Such antibradycardial pacing provides relief from symptoms and even lifesupport for hundreds of thousands of patients. Cardiac pacing may alsoprovide electrical overdrive stimulation to suppress or converttachyarrhythmias, again supplying relief from symptoms and preventing orterminating arrhythmias that could lead to sudden cardiac death.

Cardiac pacing by currently available or conventional pacemakers isusually performed by a pulse generator implanted subcutaneously orsub-muscularly in or near a patient's pectoral region. Pulse generatorparameters are usually interrogated and modified by a programming deviceoutside the body, via a loosely-coupled transformer with one inductancewithin the body and another outside, or via electromagnetic radiationwith one antenna within the body and another outside. The generatorusually connects to the proximal end of one or more implanted leads, thedistal end of which contains one or more electrodes for positioningadjacent to the inside or outside wall of a cardiac chamber. The leadshave an insulated electrical conductor or conductors for connecting thepulse generator to electrodes in the heart. Such electrode leadstypically have lengths of 50 to 70 centimeters.

Although more than one hundred thousand conventional cardiac pacingsystems are implanted annually, various well-known difficulties exist,of which a few will be cited. For example, a pulse generator, whenlocated subcutaneously, presents a bulge in the skin that patients canfind unsightly, unpleasant, or irritating, and which patients cansubconsciously or obsessively manipulate or “twiddle”. Even withoutpersistent manipulation, subcutaneous pulse generators can exhibiterosion, extrusion, infection, and disconnection, insulation damage, orconductor breakage at the wire leads. Although sub-muscular or abdominalplacement can address some concerns, such placement involves a moredifficult surgical procedure for implantation and adjustment, which canprolong patient recovery.

A conventional pulse generator, whether pectoral or abdominal, has aninterface for connection to and disconnection from the electrode leadsthat carry signals to and from the heart. Usually at least one maleconnector molding has at least one terminal pin at the proximal end ofthe electrode lead. The male connector mates with a corresponding femaleconnector molding and terminal block within the connector molding at thepulse generator. Usually a setscrew is threaded in at least one terminalblock per electrode lead to secure the connection electrically andmechanically. One or more O-rings usually are also supplied to helpmaintain electrical isolation between the connector moldings. A setscrewcap or slotted cover is typically included to provide electricalinsulation of the setscrew. This briefly described complex connectionbetween connectors and leads provides multiple opportunities formalfunction.

Other problematic aspects of conventional pacemakers relate to theseparately implanted pulse generator and the pacing leads. By way ofanother example, the pacing leads, in particular, can become a site ofinfection and morbidity. Many of the issues associated with conventionalpacemakers are resolved by the development of a self-contained andself-sustainable pacemaker, or so-called leadless pacemaker, asdescribed in the applications cited below.

Similar to active fixation implantable leads used with conventionalpulse generators, leadless pacemakers are typically fixed to anintracardial implant site by an actively engaging mechanism such as ascrew or helical member that screws into the myocardium.

Leadless pacemakers are typically delivered to an intracardial implantsite via delivery systems including catheters, sheaths and/orintroducers. These delivery systems can be complex and expensive. Also,some such delivery systems can have an associated risk of spontaneousrelease of the leadless pacemaker from the delivery system, therebyleading to unintended consequences, such as, for example, embolism.Finally, some leadless pacemakers may have an undesirably long overalllength for some instances or applications. Accordingly, there is a needin the art for systems and methods that will address thesedisadvantages.

SUMMARY OF THE DISCLOSURE

Disclosed herein is a system for delivering a leadless pacemaker havinga housing with a proximal end. In one embodiment, the system includes aguide catheter. The guide catheter includes a catheter shaft and anegative pressure (e.g., suction) attachment feature. The catheter shaftincludes a distal end and a proximal end opposite the distal end. Thesuction attachment feature is located at the distal end of the cathetershaft and configured to selectively negative pressure adhere (e.g.,suction attach) with the housing of the leadless pacemaker.

In one embodiment, the system also includes a source of negativepressure in fluid communication with the suction attachment feature. Thesource of negative pressure may include a vacuum pump or vacuum chamberattached or attachable with the guide catheter.

In one embodiment, the source of negative pressure may include anegative pressure inducing assembly on, or attachable with, the guidecatheter. The negative pressure inducing assembly may include a chamberand a member displaceable within the chamber to change a volume of thechamber. Displacing the member to increase the volume of the chamberresults in a negative pressure being communicated to the suctionattachment feature. An example of such a negative pressure inducingassembly includes a syringe.

In one embodiment, the suction attachment feature is configured to bemechanically, hydraulically or pneumatically deflected such thatdeflection of the suction attachment feature modifies its volume. Adecrease in volume causes the suction attachment feature to suctionadhere to the housing of the leadless pacemaker.

In one embodiment, the suction attachment feature includes a cupule(e.g., suction cup) with a copular (e.g., suction) chamber having asurface contour that is substantially a surface negative of the proximalend of the housing of the leadless pacemaker. The surface contour of thesuction chamber may be at least one of semi-spherical, cylindrical,conical, or parabolic.

In one embodiment, the suction attachment feature includes a suction cupwith a suction chamber having a shallow concave surface funneling to asuction lumen of the catheter shaft that daylights in the suctionchamber at a center of the suction chamber. The relatively shallowconcave surface of the suction chamber may pancake or flatten out toadhere via suction to the housing of the pacemaker.

In one embodiment, the suction attachment feature and the housing havesimilar, but opposite, concave surface contours. When the suctionattachment feature suction adheres to the housing, the suctionattachment feature goes from having a concave contour to a convexcontour to extend along and substantially contact the concave surfacecontour of the housing.

The suction attachment feature may include a concave flange. The suctionattachment feature may be formed of a polymeric material.

In one embodiment, the negative pressure attachment between the negativepressure attachment feature (e.g., cupule, suction cup, etc.) and thehousing is sufficient to transfer implantation torque from the cathetershaft to the leadless pacemaker, the transferred implantation torquebeing sufficient to tissue anchor the leadless pacemaker. In other wordsthe negative pressure attachment between the negative pressureattachment feature and the housing is sufficient that there is nodisplacement between the negative pressure attachment feature and thehousing under implant or explant torqueing of the catheter shaft.

Also disclosed herein is a method for implanting a leadless pacemaker atan implantation site in a patient. In one embodiment, the methodincludes: negative pressure (e.g., suction) adhering a housing of aleadless pacemaker to an attachment feature at a distal end of acatheter shaft, thereby coupling the catheter shaft to the leadlesspacemaker; and upon implantation of the leadless pacemaker at theimplantation site, stopping the negative pressure adhering of thehousing to the attachment feature to allow the catheter shaft to bedecoupled from the leadless pacemaker.

In one embodiment, the method also includes injecting a fluid into theattachment feature as part of the stopping or managing the adheringforces. The adhering can also include receiving a proximal end of thehousing into the attachment feature.

In one embodiment, the method is such that the negative pressureattachment between the attachment feature and the housing is sufficientthat there is no displacement between the attachment feature and thehousing under implant or explant torqueing of the catheter shaft.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity inthe claims that follow. A better understanding of the features andadvantages of the present invention will be obtained by reference to thefollowing detailed description that sets forth illustrative embodiments,in which the principles of the invention are utilized, and theaccompanying drawings of which:

FIGS. 1A and 1B are, respectively, side and end views of an exampleleadless cardiac pacemaker.

FIG. 1C is a diagrammatic medial-lateral cross section of a patientheart illustrating example implantation of leadless pacemakers in thepatient heart.

FIG. 2 is a side view of one embodiment of a delivery system fordelivering a leadless pacemaker.

FIG. 3 is an enlarged view of a distal region of FIG. 2 illustrating theleadless pacemaker and the supporting distal end of the delivery systemof FIG. 2.

FIG. 4 is an enlarged perspective view of the distal region of thedelivery system as viewed from a proximal-side vantage point.

FIG. 5 is the same view as FIG. 3, except depicting the tethered modewhereby the catheter shaft is suction coupled via the suction cup to thepacemaker housing proximal end.

FIG. 6 is the same view as FIG. 5, except illustrating the leadlesspacemaker having been released from the suction cup after implantationof the leadless pacemaker in the cardiac tissue of the implantationsite.

FIGS. 7A and 7B are end isometric views of similar suction cuparrangements.

FIG. 7C is a side view of the suction cup similar to those FIGS. 7A and7B being suction adhered to a proximal end of a leadless pacemakerhousing.

FIG. 8A is a side isometric view of another suction cup arrangement.

FIG. 8B is a side isometric view of the suction cup of FIG. 8A beingsuction adhered to a proximal end of a leadless pacemaker housing.

FIG. 9A is an end isometric view of another suction cup arrangement.

FIG. 9B is a side isometric view of the suction cup of FIG. 9A beingsuction adhered to a proximal end of a leadless pacemaker housing.

DETAILED DESCRIPTION

Disclosed herein is a negative pressure adherence (e.g., suction)equipped catheter delivery system 200 for delivering and implantingleadless pacemakers 102. The system employs a cupule (e.g., suction cup)216 at a distal end of a catheter of the system for negative pressure(e.g., suction) adhering the distal end of the catheter to a proximalend 156 of a housing 151 of the leadless pacemaker 102.

The system 200 is advantageous for a number of reasons, includingreduced manufacturing costs, increased safety (including a decreasedrisk of spontaneous release of the leadless pacemaker), and increasedease of use. The system 200 is also advantageous in that it allows forthe elimination of the tether-based docking features found at theproximal end of leadless pacemakers. Accordingly, leadless pacemakers102 configured for use with the suction equipped catheter deliverysystem 200 can have a reduced length and/or provide space for other usessuch as, for example, additional electronics, increased batterycapacity, etc.

Before beginning a detailed discussion of the delivery system andassociated method, a general overview of an example leadless pacemaker102 and implantation arrangement is provided as follows.

a. Overview of Leadless Pacemaker and Implantation Arrangement

FIGS. 1A-1B illustrate an example leadless cardiac pacemaker 102. Theleadless pacemaker 102 can communicate by conducted communication,representing a substantial departure from conventional pacing systems.The leadless pacemaker can perform cardiac pacing that has many of theadvantages of conventional cardiac pacemakers while extendingperformance, functionality, and operating characteristics with one ormore of several improvements.

In some embodiments of a cardiac pacing system, cardiac pacing isprovided without a pulse generator located in the pectoral region orabdomen, without an electrode-lead separate from the pulse generator,without a communication coil or antenna, and without an additionalrequirement of battery power for transmitted communication.

FIG. 1C illustrates an embodiment of a cardiac pacing system 150configured to attain these characteristics. The cardiac pacing system150 includes one or more leadless cardiac pacemakers 102. Each leadlesspacemaker is substantially enclosed in a hermetic housing 151 suitablefor placement on or attachment to the inside or outside of a cardiacchamber, such as the right atrium and/or right ventricle of the patientheart 152, as can be understood from FIG. 1B. Attachment of a leadlesspacemaker to the cardiac tissue can be accomplished via a helical anchor103 on an anchor mount 155 extending from a distal end of the leadlesspacemaker.

As can be understood from FIGS. 1A-1B, the leadless pacemaker 102 canhave two or more electrodes 154, 156 located within, on, or near thehousing 151, for delivering pacing pulses to muscle of the cardiacchamber and optionally for sensing electrical activity from the muscle,and for bidirectional communication with at least one other devicewithin or outside the body. The housing can contain a primary battery toprovide power for pacing, sensing, and communication, for examplebidirectional communication. The housing 151 can optionally containcircuits for sensing cardiac activity from the electrodes 154, 156. Thehousing contains circuits for receiving information from at least oneother device via the electrodes and contains circuits for generatingpacing pulses for delivery via the electrodes. The housing canoptionally contain circuits for transmitting information to at least oneother device via the electrodes and can optionally contain circuits formonitoring device health. The housing contains circuits for controllingthese operations in a predetermined manner.

As illustrated in FIG. 1A, the proximal end 157 of the housing 151 maybe shaped to facilitate negative pressure (e.g., suction) engagementbetween the proximal end 157 and a negative pressure (e.g., suction)attachment feature of the delivery system, as described below in detail.In one embodiment, the housing proximal end 157 may be of a smoothsurface having a rounded or bull-nosed surface contour, flat or planarsurface contour, or other shapes conducive to facilitating a cupule(e.g., suction cup) of the delivery system achieving adequate negativepressure (e.g., suction) attachment to the housing proximal end 157.

In some embodiments, a cardiac pacemaker can be adapted for delivery andimplantation into tissue in the human body. In a particular embodiment,a leadless cardiac pacemaker can be adapted for implantation adjacent toheart tissue on the inside or outside wall of a cardiac chamber, usingtwo or more electrodes located on or within the housing of thepacemaker, for pacing the cardiac chamber upon receiving a triggeringsignal from at least one other device within the body.

Leadless pacemakers or other leadless biostimulators are typically fixedto an intracardial implant site by an actively engaging mechanism orprimary fixation mechanism such as a screw or helical member 103 thatscrews into the myocardium. Examples of such leadless biostimulators aredescribed in the following publications, the disclosures of which areincorporated by reference: (1) US Publication No. US2007/0088394; (2) USPublication No. US2007/0088396; (3) US Publication No. US2007/0088397;(4) US Publication No. US2007/0088398; (5) US Publication No.US2007/008400A1 on Apr. 19, 2007; (6) US Publication No. US2007/0088405;(7) US Publication No. US2007/0088418; and (8) International PublicationNo. WO07047681.

In addition to the primary fixation mechanism, such as a helix, someleadless biostimulators may further include a secondary fixationmechanism to provide another feature for keeping the leadlessbiostimulator in place within the body. Secondary fixation mechanismscan be either active (e.g., the secondary fixation mechanism canactively engage tissue, either within or outside the heart), or can bepassive (e.g., the secondary fixation mechanism is not attached totissue but rather prevents the leadless biostimulator from moving aroundin the body in the case of accidental detachment). Further details onsecondary fixation mechanisms can be found in U.S. application Ser. No.12/698,969.

Leadless pacemakers or other leadless biostimulators can be delivered toand retrieved from a patient using any of the delivery systems describedbelow. As discussed below in detail, the leadless pacemaker is attachedor connected to the delivery system via negative pressure adherence(e.g., suction) and advanced intravenously into the heart. The deliverysystem includes a cupule with a copular chamber (e.g., suctionattachment feature) configured to engage the leadless pacemaker to thedistal end of the delivery system to allow the delivery system to beused to deliver the leadless pacemaker to the implantation site and fixthe leadless pacemaker to the tissue of the implantation site.

b. Suction Equipped Catheter System for Leadless Pacemaker Implantation

FIG. 2 is a side view of one embodiment of a delivery system 200 fordelivering a leadless pacemaker 102. As shown in FIG. 2, the pacemakerdelivery system 200 includes a delivery sheath 204, guide catheter shaft211, introducer 207, catheter control handle 208, deflection knob 210,suction control 212, flush ports 214A and 214B, protective sleeve 215,suction line 217, and suction system 218.

The guide catheter includes the handle 208 and catheter shaft 211, whichextends distally from the distal end of the handle to a distal end ofthe catheter shaft 211. The distal end of the catheter shaft includes acupule (e.g., suction attachment feature 216 that suction couples withthe proximal end 157 of the leadless pacemaker 102, as described indetail below.

The catheter shaft 211 is both flexible and torqueable. Depending on theembodiment, the catheter shaft 211 may be formed of a polymericconstruction and/or metal construction. For example, the catheter shaft211 may have a traditional catheter lamination construction or have ahollow-helical cable construction.

The deflection knob 210 and suction control 212 are part of the catheterhandle 208 at the proximal end of the catheter. The deflection knob maybe coupled with deflection members or cables that extend through lumensof the catheter shaft, as known in the art. These deflection members orcables are distally-proximally displaceable relative to the rest of thecatheter shaft. Thus, the deflection knob 210 can be used to steer andguide the catheter shaft 211 during implantation and/or removal of thepacemaker.

A suction line 217 extends between the suction system 218 and a proximalend of the handle 208. The suction system 218 is fluidly coupled, viathe suction line 217, with a proximal end of a suction lumen 219 (seeFIGS. 2 and 3) that extends through the catheter handle 208 and cathetershaft 211 to the suction attachment feature 216. The suction control 212is configured to allow the user to selectively operate the suctionattachment feature 216 between suction “on” and suction “off”, therebyallowing the suction attachment feature 216 to adhere via suction to theproximal end 157 of the leadless pacemaker or to decouple therefrom,respectively.

In one embodiment, the suction system may take the form of a vacuum pumpor vacuum chamber that provides a source of negative pressure in fluidcommunication with the suction attachment feature. The vacuum pump orvacuum chamber may be attached or attachable with the guide catheter.

In one embodiment, the suction system may take the form of a source ofnegative pressure that includes a negative pressure inducing assemblyon, or attachable with, the guide catheter. For example, such a negativepressure inducing assembly may include a chamber and a memberdisplaceable within the chamber to change a volume of the chamber.Displacing the member to increase the volume of the chamber results in anegative pressure being communicated to the suction attachment feature).In one embodiment, such a negative pressure inducing assembly may be inform of, or include, a syringe. The syringe, or similar negativepressure inducing assembly, may be fluidly coupled to the catheter, andmore specifically, the suction attachment feature 216. Alternatively,the syringe, or similar negative pressure inducing assembly, may bebuilt into the catheter, for example, in the handle of the catheter.

In one embodiment, the negative pressure (e.g., suction) system may takethe form of a mechanism by which the cupule (e.g., suction attachmentfeature) is deflected to change its shape and, as a result, its volume.A decrease in the volume of the suction attachment feature as it ispressed against the housing of the leadless pacemaker causes the suctionattachment feature to suction adhere to the housing.

Depending on the embodiment, a mechanical arrangement in the form of acable, rigid rod, or hydraulic or pneumatic lumen may extend through thecatheter shaft from its attachment with the suction attachment feature.Displacement of the mechanical arrangement causes deflection in thesuction attachment member such that its suction volume reduces. Thisreduction results in a negative pressure condition when pressed againstthe pacemaker housing, thereby causing the suction attachment feature tosuction adhere to the housing. Deflection of the cupule (e.g.,suction/negative pressure attachment feature) via the mechanicalarrangement in an opposite direction will eliminate the negativepressure condition and allow the pacemaker to decouple from thecatheter.

The catheter shaft 211 extends through the delivery sheath 204, whichextends proximally from the protective sleeve 215 to the proximal flushport 214B. The protective sleeve forms the distal end of the deliverysheath. The delivery sheath 204 extends through the introducer 207,which extends distally from the distal flush port 214A. The cathetershaft 211 is longer than the delivery sheath 204, and the deliverysheath 204 is substantially longer than the introducer 207.

The delivery sheath 204 can be distally-proximally displaced within theintroducer 207. The catheter shaft 211 can be distally-proximallydisplaced within the delivery sheath 204 such that the leadlesspacemaker, which is suction attached to the suction attachment feature216, can be proximally retracted relative to the delivery sheath 204 toreside within the confines of the protective sleeve 215 or distallyextended relative to the delivery sheath 204 to be distal the protectivesleeve 215, as depicted in FIG. 2. Thus, the delivery sheath 204 can beadvanced distally over the catheter shaft 211 to provide additionalsteering and support for the delivery catheter shaft 211 duringimplantation and to surround the pacemaker 102 as it is introducedthrough a trocar or introducer 207 into the patient and negotiatedthrough the patient's vasculature to the implantation site.

The flush ports 214A and 214B can be used to flush saline or otherfluids through the shaft of the introducer 207 and the delivery sheath204, respectively.

FIG. 3 is an enlarged view of the circled distal region of FIG. 2illustrating the leadless pacemaker and the suction/negative pressureattachment feature 216 suction coupled to the curved or bull-nosedproximal end 165 of the housing 151 of the leadless pacemaker 102 ofFIGS. 1A and 1B. FIG. 4 is an isometric view of the same situationillustrated in FIG. 3. As illustrated in FIGS. 3 and 4, the deliverysheath 204 is shown pulled back proximally along the guide cathetershaft 211 to fully expose the pacemaker 102, including its distalhelical tissue anchor 103.

Conversely and although not specifically illustrated, it can beunderstood that the delivery sheath 204 can be extended distally alongthe guide catheter shaft 211 to fully cover the pacemaker 102 by causingthe pacemaker 102 to fully reside within the confines of the protectivesleeve 215. Thus, the cardiac tissue is fully protected from the sharpedges of the helix 103 during implantation.

In summary, when the protective sleeve 215 is pulled back proximally, asshown in FIG. 3, the pacemaker 102 is in an exposed, implantationconfiguration. When the protective sleeve 215 is advanced distally toprotect the pacemaker and helix, the pacemaker 102 is in a protected,advancement configuration.

As can be understood from FIGS. 3 and 4, in one embodiment, the cupule(e.g., suction attachment feature) 216 may be in the form of a cupularchamber (e.g., negative pressure cup, vacuum cup or suction cup) 216that engages the housing proximal end 156 of the leadless pacemaker 102when a negative pressure (e.g., suction, vacuum, etc.) is administeredto the suction cup 216. The negative pressure is generated by thesuction system 218 (see FIG. 2) and communicated to the suction cup 216via the suction lumen 219 of the catheter shaft 211. The suction lumen219 distally terminates within the confines of the suction cup 216.

As illustrated in FIGS. 3 and 4, the proximal end 156 of the pacemakerhousing 151 is docked with the suction cup. Specifically, the proximalend 156 of the pacemaker housing 151 is first received in the confinesof the suction cup 216. The suction cup is then adhered to the housingproximal end 156 by placing the suction cup 216 in fluid communicationwith the suction system 218 via actuating the suction control 212 on thecatheter handle 208. With the leadless pacemaker 102 attached in such asuction manner to the suction cup, the delivery of the leadlesspacemaker to the implantation site can then take place as follows.

During initial insertion of the delivery system 200 into a patient, aphysician can gain access to the patient's venous system with theintroducer sheath 207 using the Seldinger technique (not shown), Thedelivery system 200, including the leadless pacemaker 102, cathetershaft 211, and delivery sheath 204 can then be advanced through theintroducer sheath 207 into the patient's venous system to facilitatedelivery of the pacemaker 102 into the heart.

After the delivery system 200 is inserted through the introducer sheath207 into the patient, the protective sleeve 215 can be advanced distallyover the leadless pacemaker by causing the delivery sheath 204 todistally displace along the catheter shaft 211. With the protectivesleeve 215 isolating the leadless pacemaker 102 and its helical anchorfrom the surrounding tissue, the leadless pacemaker can be trackedthrough the patient's venous system to the implantation site in thepatient's heart. Upon reaching the implantation site, the protectivesleeve 215 can be retracted proximally from about the leadless pacemakerby causing the delivery sheath 204 to proximally displace along thecatheter shaft 211. The leadless pacemaker 102, catheter shaft 211 andprotective sleeve 215 now appear as depicted in FIGS. 3 and 4.

FIG. 5 is the same view as FIG. 3, except depicting the tethered modewhereby the catheter shaft 211 is suction coupled via the suction cup216 to the pacemaker housing proximal end 156. The tethered mode allowsfor positioning and repositioning of the leadless pacemaker 102 againsta cardiac tissue surface 220. The tethered mode also allows for screwingof the helical anchor 103 into or out of the cardiac tissue to achieveimplantation or explantation of the leadless pacemaker, respectively.

As can be understood from FIG. 5, the catheter shaft 211 is flexible soas to deflect as necessary when the pacemaker distal end is forcedagainst the cardiac tissue surface 250. Also, as indicated by arrow A inFIG. 5, the catheter shaft 211 is capable of transmitting torque fromthe handle to the attached pacemaker 102 to screw the helical anchor 103into, or out of, the cardiac tissue 220 to result in implantation orexplantation of the leadless pacemaker, respectively.

FIG. 6 is the same view as FIG. 5, except illustrating the leadlesspacemaker 102 having been released from the suction cup 216 afterimplantation of the leadless pacemaker in the cardiac tissue 220 of theimplantation site. Specifically, the helical anchor 103 of the implantedleadless pacemaker 102 is now fully imbedded in the cardiac tissue. Toachieve the released condition, the negative pressure of the suctionsystem 218 (see FIG. 2) is isolated from the suction cup 216 byactuating the suction control 212 of the catheter handle 208 to suction“off”. Alternatively or additionally to shutting off the negativepressure at the suction cup, a puff of saline can be administeredthrough the suction lumen 219 to the suction cup 216 to help push thepacemaker housing proximal end 156 out of the confines of the suctioncup 216.

With the implanted leadless pacemaker 102 now decoupled from thedelivery system 200, the delivery system can now be withdrawn from thepatient, leaving behind the implanted leadless pacemaker, as illustratedin FIG. 6. Advantageously, there would be minimal to no “tug” on cardiactissue during release of the pacemaker from the suction cup, since inthe absence of vacuum, suction, or some form of negative pressure, thepacemaker and the suction cup are not attached to each other. As aresult, the catheter is simply allowed to float away from the implantedpacemaker, therefore preventing tissue trauma.

While the implantation of the leadless pacemaker via the delivery system200 can take place as described immediately above, the process ofexplantation of an implanted leadless pacemaker can be achieved via thesame process in reverse. For example and by way of summary, the suctioncup 216 is first moved towards the housing proximal end 156 of theimplanted leadless pacemaker 102, as can be understood from FIG. 6. Theleadless pacemaker 102 is docked with the suction cup 216 by causing thehousing proximal end 156 to be received in the confines of the suctioncup, and suction is administered to the suction cup to complete thedocking process, as can be understood from FIGS. 3 and 4. Torque is thenapplied to the catheter shaft 211 to unscrew the helical anchor 103 fromthe cardiac tissue 220, as can be understood from FIG. 5. The leadlesspacemaker 102 can then be covered by the protective sleeve 215 byadvancing the delivery sheath 204 distally relative to the cathetershaft 211. With the leadless pacemaker 102 so isolated from thesurrounding patient vasculature structures, the delivery system andleadless pacemaker can be withdrawn from the patient.

The above-described suction based leadless pacemaker delivery/retrievalsystem 200 may employ a variety of suction cup embodiments. For example,the suction cup 216 may have a single geometric profile or a pluralityof three dimensional geometric profiles. Regardless of the profileconfiguration, each suction cup embodiment is shaped in such a way tofacilitate adequate suction/negative pressure adherence to the proximalend 156 of the pacemaker housing 151. Correspondingly, the proximal end156 of the pacemaker housing 151 is shaped in such a way that thesuction cup 156 adheres thereto via a vacuum or suction state existingbetween the proximal end 156 and the suction cup 216. Thus, the suctioncup and proximal end of the pacemaker housing are complimentarilyconfigured such that suction adherence of the suction cup 216 to theproximal end 156 is sufficient to maintain the leadless pacemakerattached to the delivery system 200 and allow for adequate torquetransmission for implantation or explantation of the leadless pacemaker.

As can be understood from FIG. 6, in one embodiment, the inner confinesor suction chamber 222 of the suction cup 216 has a surface contour 224that is substantially a surface negative of the outer surface of thepacemaker housing proximal end 156, although the size and volume of thesuction chamber 222 exceeds that of the housing proximal end 156 tofacilitate the proximal end 156 being received in the suction chamber222. As can be understood from FIG. 5, when the housing proximal end 156is received in the suction chamber 222, the opposite surfaces 156, 224generally make continuous mating surface contact. This surface contactis increased upon application of the negative pressure communicated viathe suction lumen 219, which daylights in the suction chamber 222 at thecenter of the suction chamber 222.

In the embodiment depicted in FIG. 6, the opposite surfaces 156, 224 aresemi-spherical. However, in other embodiments, the pacemaker housingproximal end 156 may have other shapes (e.g., conical, cylindrical,parabolic, etc.), and the suction chamber 222 and its surface contour224 will be a surface negative of the shape of the proximal end 156.

In some embodiments as reflected by the suction cups of FIGS. 7A and 7B,the suction chamber 222 is much less spherical than the embodiment ofFIG. 6. Instead the suction chamber 222 of FIGS. 7A and 7B may be in theform of a relatively shallow concave surface 224 funneling to thesuction lumen 219, which daylights in the suction chamber 222 at thecenter of the suction chamber. The size of the suction lumen 219termination in the suction chamber 222 may be smaller, as shown in FIG.7A, or larger, as depicted in FIG. 7B. In either case, as depicted inFIG. 7C, the pacemaker housing proximal end 156 may be a flat ortruncated end of a cylindrical housing shape, and the concave surface224 of the suction chamber 222 may simply pancake or flatten out toadhere via suction to the flat proximal end 156.

As illustrated in FIG. 8A, the suction chamber 222 may have a concavesurface contour 224 that is more spherical than those of FIGS. 7A and 7Band still not be substantially or fully semi-spherical like theembodiment of FIG. 6. As can be understood from FIG. 8A, the housingproximal end 156 is a similar, but opposite, concave surface contour ascompared to that of the suction chamber of FIG. 8A. As shown in FIG. 8B,when the suction cup 216 is suction adhered to the housing proximal end156, the suction cup goes from having a concave contour to a convexcontour where the suction cup surface 224 extends along andsubstantially contacts the concave surface of the housing proximal end156.

In one version of the embodiment depicted in FIGS. 8A and 8B, thehousing proximal end 156 may be a rigid flange having the depictedconcave configuration. Alternatively, in another version of theembodiment depicted in FIGS. 8A and 88, the housing proximal end 156 maybe a flexible/compliant flange having the depicted concaveconfiguration, the flexible/compliant flange deforming in acomplementary fashion with the suction chamber 222 when the suction cup216 is suction adhered to the flexible/compliant flange of the housingproximal end 156. In addition to providing strong suction adherence, theflanged proximal end 156 of the embodiment depicted in FIGS. 8A and 8Bcan provide a feature for retrieval via a delivery/retrieval systememploying a snare/grasper arrangement in place of, or in addition to,the suction cup.

As depicted in FIG. 9A, in some embodiments, the suction cup 216 has asuction chamber 222 that is substantially cylindrical, and the exteriorof the suction cup may be similarly cylindrical. As shown in FIG. 9B,such a suction cup 216 does not measurably deflect when suction adheredto a planar proximal end 156 of the pacemaker housing 151.

The suction cup 216 is made of one or more polymeric materials such as,for example, silicone, rubber, polyurethane, siliconerubber-polyurethane-copolymer (“SPC”), or other appropriatebiocompatible pliable materials. Depending on the configuration of thesuction cup, the suction cup materials may be highly pliable, relativelystiff or something in between.

In summary, the above-described delivery/retrieval system 200 employs asuction based mechanism used for providing torque transmission as wellas the coupling between the system 200 and leadless pacemaker 102 inachieving the delivery and implantation of the leadless pacemaker 102 orother type of implant. The suction/negative pressure based mechanism 216includes a suction cup, vacuum cup, suction flange, or other suctionfeature that stays attached or grasps onto features of the pacemakerwith the help of suction/vacuum applied via internal channels within thedelivery catheter. When the suction/vacuum is turned off, the suctioncup detaches from the pacemaker, thus detaching the pacemaker from thedelivery system. As a result, the delivery system can simply float awayfrom the implanted pacemaker without tugging on the tissue orcompression on the catheter.

The system 200 disclosed herein is advantageous for a number of reasons.For example, the system presents a reduced risk of spontaneous orundesired release of an implant from the catheter. The system alsoprovides reliable detachment that is independent of the relativeposition of the system to the pacemaker.

The system isolates rotation implant forces from the attachmentmechanism, thereby eliminating possible binding issues associated withother delivery systems. The system also provides minimal-to-no “tug” ontissue during detachment due to the suction cup simply ceasing to adhereto the pacemaker once the negative pressure is no longer beingadministered to the suction cup.

The system is easy to use in that it is tool-less and configured forbed-side loading since the suction cup can be attached and detached fromthe pacemaker simply by turning on and off the suction (respectively).Thus, the system can be used at the bed-side of a patient withoutexhaustive training, or fixtures. This system feature is veryadvantageous when multiple implants, such as cardiac pacemakers, need tobe implanted inside the anatomy. For example, the system may be used todeliver the first implant/pacemaker. The same system may then be removedfrom the body, loaded with another implant/pacemaker at the patient'sbed-side, and delivered to the implant site as a second implant.

The system offers simple interface mechanisms for delivering torque andfacilitating attachment and detachment of a leadless pacemaker. Finally,the system can eliminate the attachment features of the leadlesspacemaker that are used with snare or grasping delivery systems, therebyfreeing up the real estate of the leadless pacemaker for other uses.

As for additional details pertinent to the present invention, materialsand manufacturing techniques may be employed as within the level ofthose with skill in the relevant art. The same may hold true withrespect to method-based aspects of the invention in terms of additionalacts commonly or logically employed. Also, it is contemplated that anyoptional feature of the inventive variations described may be set forthand claimed independently, or in combination with any one or more of thefeatures described herein. Likewise, reference to a singular item,includes the possibility that there are plural of the same itemspresent. More specifically, as used herein and in the appended claims,the singular forms “a,” “and,” “said,” and “the” include pluralreferents unless the context clearly dictates otherwise. It is furthernoted that the claims may be drafted to exclude any optional element. Assuch, this statement is intended to serve as antecedent basis for use ofsuch exclusive terminology as “solely,” “only” and the like inconnection with the recitation of claim elements, or use of a “negative”limitation. Unless defined otherwise herein, all technical andscientific terms used herein have the same meaning as commonlyunderstood by one of ordinary skill in the art to which this inventionbelongs. The breadth of the present invention is not to be limited bythe subject specification, but rather only by the plain meaning of theclaim terms employed.

What is claimed is:
 1. A system, comprising: a leadless pacemakerincluding a housing having a proximal end; and a guide catheterincluding an attachment feature of a catheter shaft, wherein theattachment feature is configured to selectively adhere to the housing ofthe leadless pacemaker via a negative pressure between the proximal endof the housing and an opposing surface of the attachment feature.
 2. Thesystem of claim 1 further comprising a source of the negative pressurein fluid communication with the attachment feature.
 3. The system ofclaim 2, wherein the source of the negative pressure includes a vacuumpump or a vacuum chamber attached or attachable with the guide catheter.4. The system of claim 2, wherein the source of the negative pressureincludes a negative pressure inducing assembly on, or attachable with,the guide catheter.
 5. The system of claim 4, wherein the negativepressure inducing assembly includes a chamber and a member displaceablewithin the chamber to change a volume of the chamber, wherein displacingthe member to increase the volume of the chamber results in the negativepressure being communicated to the attachment feature,
 6. The system ofclaim 5, wherein the negative pressure inducing assembly includes asyringe.
 7. The system of claim 1, wherein the attachment feature isconfigured to be mechanically, hydraulically, or pneumatically deflectedsuch that deflection of the attachment feature modifies an attachmentfeature volume, and a decrease in the attachment feature volume causesthe attachment feature to adhere to the housing of the leadlesspacemaker,
 8. The system of claim 1, wherein the attachment featureincludes a cupular chamber including the opposing surface having asurface contour that is substantially a surface negative of the proximalend of the housing of the leadless pacemaker.
 9. The system of claim 8,wherein the surface contour of the cupular chamber is at least one ofsemi-spherical, cylindrical, or conical.
 10. The system of claim 1,wherein the attachment feature includes a cupular chamber having ashallow concave surface funneling to a suction lumen of the cathetershaft that daylights in the cupular chamber at a center of the cupularchamber.
 11. The system of claim 10, wherein the shallow concave surfaceof the cupular chamber pancakes or flattens out to adhere via thenegative pressure to the housing of the leadless pacemaker.
 12. Thesystem of claim 1, wherein the attachment feature and the leadlesspacemaker have similar, but opposite, concave surface contours, and whenthe attachment feature adheres to the housing, the opposing surface ofthe attachment feature goes from having a concave contour to a convexcontour to extend along and substantially contact the concave surfacecontour of the housing.
 13. The system of claim 1, wherein theattachment feature includes a concave flange.
 14. The system of claim 1,wherein the attachment feature is formed of a polymeric material. 15.The system of claim 1, wherein the negative pressure between theattachment feature and the housing is sufficient to transfer animplantation torque from the catheter shaft to the leadless pacemaker.16. The system of claim 15, wherein the leadless pacemaker includes atissue anchor, wherein the negative pressure between the attachmentfeature and the housing is sufficient to transfer the implantationtorque to screw the tissue anchor into tissue without displacementbetween the attachment feature and the housing.